Transmission methods for a downlink data channel include localized transmission and distributed transmission.
In localized transmission, as shown in FIG. 1A, frequency resources are allocated to the respective users by frequency blocks. For example, in localized transmission, frequency blocks are allocated in such a manner that frequency selective fading is reduced. Generally, transmission data sizes in localized transmission are large, and therefore localized transmission is suitable to achieve the effect of frequency scheduling.
As shown in FIG. 1B, in distributed transmission, transmission data are distributed across an allocated frequency band regardless of frequency blocks. For example, distributed transmission is employed when frequency scheduling is not usable because users are moving at high speed or when transmission data sizes are small as in VoIP. Generally, transmission data sizes in distributed transmission are small, and therefore distributed transmission is suitable to achieve frequency diversity gain.